Excitonic and Quasiparticle Life Time Effects on Silicon Electron Energy Loss Spectrum from First Principles

TL;DR

This paper uses first-principles GW calculations to analyze quasiparticle decay and lifetimes in silicon, enabling accurate computation of the electron energy loss spectrum and plasmon features without empirical broadening.

Contribution

It introduces a method to incorporate quasiparticle lifetimes into the dielectric function calculation from first principles, improving spectral predictions.

Findings

Quasiparticle lifetimes in silicon are characterized by electron-electron interactions.

The complex dielectric function can be computed without empirical broadening.

The electron energy loss spectrum and plasmon peak are accurately described.

Abstract

The quasiparticle decays due to electron-electron interaction in silicon are studied by means of first-principles all-electron GW approximation. The spectral function as well as the dominant relaxation mechanisms giving rise to the finite life time of quasiparticles are analyzed. It is then shown that these life times and quasiparticle energies can be used to compute the complex dielectric function including many-body effects without resorting to empirical broadening to mimic the decay of excited states. This method is applied for the computation of the electron energy loss spectrum of silicon. The location and line shape of the plasmon peak are discussed in detail.